New Diet Pills Raise Old Safety Questions

Published: February 21, 1996

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There is therefore a fear that Redux may cause problems in the same mood-regulating system. Dr. Lewis Seiden, a pharmacologist at the University of Chicago who was one of several critics who testified against the approval of the drug before the agency's advisory panel, said he and others had published studies of the drug or a closely related one in different animal species. He said they had shown that after taking the drug for some time and then stopping, the animals had severely depleted levels of serotonin.

In humans, that might be expected to produce a sudden severe depression or bursts of impulsive behavior, he said.

In rats, Dr. Seiden said, the levels of serotonin "stay down weeks and months after we stopped giving the drug."

"In monkeys," he said, "there are reports that the levels remain low for up to 17 months. At some point, you worry that damage has been done and you may not be able to bring the level back."

He added, "The company says that they will do postmarketing surveillance to keep an eye on this in humans. They think humans are an exception, and that it is safe. But my argument is that once it's approved it is very tough to get it disapproved. These studies should be done prior to marketing, not afterward."

The company counters that the doses used in people will be somewhat lower than those used in animals and that in humans the serotonin levels rise back to normal. A simple precaution to prevent trouble is to stop use of the drug only slowly. Another possibility, the company says, is to keep using it permanently.

The company has already done studies in humans that kept track of the psychological health of those on the drug and reported that people who took the drug showed no mental problems associated with it. The patients have not, however, been followed for more than a few months.

Those who favor using drugs to help give people an edge in the fight against fat say that it is time to stop thinking of obesity as just an issue of willpower.

And Dr. Weintraub of the drug agency said that because the condition was both serious and continuing, it probably should be treated continuously rather than in bursts of occasional dieting.

But the availability of an effective obesity treatment with potentially serious side effects would raise the problem of how doctors are to determine what level of obesity warrants drug treatment.

Dr. David Rothmann of Columbia University's College of Physicians and Surgeons said: "The pressures to be thin are very great. So with this drug there may well be some 'definition slippage.' Being fat at obese levels kills. At, say, double your ideal body weight this is very serious business. But once the drug is out there in the hands of doctors, they don't have to prescribe it only for people who are grossly overweight."

"Pretty soon, you'll see people who are five pounds overweight coming in to ask their doctor for some help in slimming down," he said, and suggested that the drug had serious effects on the brain that should not be taken so lightly. "Millions of people will be on this drug, for years at a time," he said. "We ought to be careful."

Dr. Weintraub, who ardently favors developing new drugs to deal with obesity, said that last point was the one that worried him. Doctors, he said, "take high blood pressure, diabetes and similar ailments seriously, taking time with patients to interview them and talk to them about options. But for some reason, weight loss seems to attract those who are only in it for the money. I hope that can change."